In order to maintain competitive capability of the third generation mobile communication system in the field of communication, provide users with faster speed, shorter delay, and more personalized mobile services, and meanwhile reduce the operator's operating costs, the 3rd Generation Partnership Project (referred to as 3GPP) standards working group is working on the Evolved Packet system (Evolved Packet System, referred to as EPS) research. FIG. 1 shows the structural diagram of the evolved packet domain system, and as shown in FIG. 1, the entire EPS system is divided into two parts: a radio access network and a core network. The core network comprises home subscriber server (referred to as HSS), mobility management entity (referred to as MME), Serving GPRS Support Node (referred to as SGSN), policy and charging rule function (referred as PCRF), serving gateway (referred to as S-GW), packet data network gateway (PDN Gateway, referred to as P-GW) and packet Data Network (referred to as PDN). In the following, the function of each part will be described in detail.
The home subscriber server is a permanent storage site for user subscription data and is located at the user subscribed home network.
The mobility management entity is a storage site for the user subscription data in the current network, and is responsible for the terminal-to-network non-access layer signaling management, terminal security authentication function, terminal mobility management, tracking and paging management function in the user idle mode, and bearer management.
The serving GPRS support node is a service support node for users in the Global System for Mobile Communications (referred to as GSM) Enhanced Data Rate for GSM Evolution (referred to as EDGE) Radio Access Network (referred to as GERAN) and the Universal Mobile Telecommunications System (referred to as UMTS) terrestrial radio access network (referred to UTRAN) to access the core network, it is similar to the mobility management entity in functionality, and responsible for user location update, paging management, bearer management, and other functions.
The serving gateway is a gateway from the core network to the radio system and is responsible for the user plane bearer from the terminal to the core network, data buffering in the terminal idle mode, function of initiating a service request by the network side, lawful interception, packet data routing and forwarding function; the serving gateway is responsible for collecting the cases of the user terminal using the radio network, producing the charging bill of the terminal using the radio network, and sending it to the charging gateway.
The packet data gateway is a gateway of the LTE system and the external packet data network of the system, it connects with the Internet and the packet data network, and is responsible for Internet protocol (referred to as IP) address allocation, charging function, packet filtering and policy control of the terminal, etc.
The packet data network is an operator's IP service network, and the network provides IP services to users through the operator's core network.
The policy and charging rule function entity is a server responsible for providing the charging control, online credit control, threshold control, and Quality of Service (referred to as QoS) policy rule in the evolved system.
The radio access network consists of an Evolved NodeB (referred to as eNB) and a 3G radio network controller (referred to as RNC), and it is mainly responsible for transmitting and receiving radio signals, contacting with the terminal over the air interface, managing the radio resources of the air interface, resource scheduling and access control.
The serving GPRS support node is an upgraded SGSN, and it supports the S4 interface to the serving gateway, and interacts with the mobility management entity MME by using the GPRS Tunneling Protocol Version 2 (referred to as GTPv2). For the SGSN supporting the 3G core network, the packet switching (referred to as PS) domain network architecture is different from what is shown in FIG. 1. At this point, the SGSN and the MME are connected via the Gn interface, and the interaction uses the GPRS Tunneling Protocol version 1 (referred to as GTPv1). The SGSN cannot connect with the serving gateway, but it directly accesses to the packet data network by connecting to the gateway GPRS support node (referred to as GGSN) via the Gn interface.
The Home NodeB (referred to as the HNB) or Home eNodeB (referred to as HeNB) is a type of a small, low power nodeB, and works as some users' dedicated resources deployed in families, groups, corporations, colleges, or other private places for use, it is primarily used to provide the users with higher-speed services and reduce the cost required for using the high-speed services, and meanwhile compensate for the lack in coverage of the distributed cellular wireless communication system. Advantages of the home nodeB are that it is affordable, convenient, has low power output, plug and play, and broadband access, and uses single-mode terminals.
The home nodeB can directly connect to the core network, as shown in FIG. 2a, or access to the core network through the logic network element, i.e. home nodeB gateway, as shown in FIG. 2b, wherein, the main functions of the home nodeB gateway are: authenticating the home nodeB's security, dealing with the home nodeB's registration, operating, maintaining and managing the home nodeB, and configuring and controlling the home nodeB according to the operator requirements, and being responsible for exchanging data between the core network and the home nodeB.
In order to achieve the local access functions (including local IP access (referred to as LIPA) or Selected IP Traffic Offload (referred to as SIPTO), i.e., for a local access by the terminal to other IP devices in the home network, the IP devices in the corporate network, or the Internet, a local gateway is added, as shown in FIG. 3. The addition of the local access gateway provides a strong support for local access technology, and the local gateway can be located at the same place of the network element in the radio network or in the vicinity of the network element in the radio network (i.e. external). The local gateway comprises a local PGW (referred to as L-GW), a local GGSN (referred to as L-GGSN), and has partial PGW and GGSN functionality.
In the mobile communications network architecture, the data flow paths of the local access and the traditional core network access are shown in FIG. 3. For users supporting the local access, the traditional core network access data path and the local access data path can be established simultaneously. For the local access connection, the local access data path is from the terminal to the network element at the radio side, and then to the local access gateway (such as L-PGW and L-GGSN), and further access to the local network resources, and the data traffic does not go through the core network. In order to achieve the local access of the terminal to other IP devices in the home network or the Internet, two connections can be created, the first local access data path directly accesses to the Internet (Internet IP connection, that is, SIPTO connection). The second local access data path directly accesses to other IP devices in the home network (home network IP connection, that is, LIPA connection).
The local network resources composed of IP devices in a home or corporate network are only used by users who are authorized to access the local network, and such users have local access subscription information stored in the HSS. When a user is a connected state, if the local access subscription information dynamically changes, there is no solution on how the network deals with the local access connections that have already been activated.